Eating Organic, Local, and Seasonal Foods

Go get the Shopper's Guide to Pesticides in Produce from Environmental Working Group. Here I list the top 14 (i.e., worst) and bottom 14 (i.e., safer) from the list (note that ranking varies each year). For the top 14, buy organic to lower your exposure to pesticides. If you cannot afford organics, you can take a look at which produce is the safest to buy conventionally. To get the full list, check out here.
Use the following guidelines for choosing your foods:

Buy organics

Look for locally grown produce

Enjoy seasonal food (for San Mateo County see [1])

Buy foods from farmer's markets instead of supermarkets

Eat more foods on the wild/bitter side[11,12]

Why Organic?

Organic produce comes from farmers who have been certified by a state-recognized organization. They have to demonstrate that their methods replenish and maintain the soil's natural fertility and reduce the impact of farming on the environment.

Single-crop commercial farmers compensate for soil depletion by adding chemical fertilizers and get rid of pests with toxic pesticides and weed-killers. Organic farmers enrich the soil by alternating crops and feeding it with compost, manure and plant wastes, plant cover crops such as clover to choke out weeds and get rid of pests with a range of non-toxic methods. Example: releasing beneficial insects that attack plant-destroying organisms. Organic crops are grown in this way in the soil that has been free of these chemicals for at least 3 years. Similarly, organically raised animals aren't treated with antibioticsor growth hormones and are given natural feed or, even better, raised on pasture (grass fed).

Is organic more nutritious? Maybe yes although the finding is preliminary. Recently a handful of well-conducted comparisons of crops grown organically and conventionally have found appreciably higher levels of antioxidants, flavonoids, vitamins, and other nutrients in several of organic crops. Plus, toxic substances from the environment, feed, and drugs can
actually be concentrated in the flesh of animals in a process called
bioaccumulation. To minimize your own toxic load is by eating
organic products, both plant and animal.
Another reason for you to consider buying organic is supporting farms that grow food in ways that are more friendly to the environment (i.e., generate less waste, cause less soil erosion, sustain more diversity, etc.). Also, my own experience of buying organic foods from farmer's markets is that the foods taste better and they can remain fresher longer.

Label

What It Means[3]

100% organic

Means just what it says.

Organic

At least 95% or more of the ingredients must be organic

Made with organic ingredients

At least 70% of the ingredients are organic.

Natural [4]

Natural does not mean organic. In fact, it has no standard definition so there’s no point in paying more for a food just because it claims to be natural.

Why Local?

Local food endures minimal nutritional loss by the time you eat it.

Local foods are picked at the peak of ripeness, while foods that have to travel are picked before they've reached peak.

Fruits should be eaten as soon as they ripe. If you let them sit longer, they'll produce more and more sugar, which will drive up their Glycemic Load.

Most of the fruit we buy in the stores are picked green and then gassed to help them ripen to send to market.

Local produce is less likely to have been treated with post-harvest pesticides.

Local food generally uses less packaging.

By eating local food, you support the local economy.

To prolong shelf life and ship foods to far-away places, sometimes irradiation is used to kill nasty bacteria like E-coli. For example, Hawaii papaya found in California sometimes is irradiated. Also, most Hawaiian papaya is genetically engineered to be ringspot virus-resistant and banned by EU.[13]

Why Eat The Seasons?

To reduce the energy (and associated CO2 emissions) needed to grow and transport the food we eat.

To avoid paying a premium for food that is scarcer or has traveled a long distance.

To reconnect with nature's cycles and the passing of time.

To eat food that is fresher and tastier.

You can check out Eat The Seasons web site to find out which foods are in season each week.

Why Farmer's Market?
In the "Secrets Supermarkets Don’t Want You to Know" segment of Dr Oz Show, it shows that produce misters in the supermarkets are often moldy and spread mold and dangerous bacteria. Some misters even recirculate the water! The investigation also finds out that conveyor belts in the supermarket harbor dangerous germs. If you shop at farmer's market, you can avoid both issues. Finally, if you buy from farmer's market, you also buy local.